My truck is a 97, F-150 4X4 with the 4.6. (E40D Trans). While driving, my truck shakes for a few seconds, stops, then shakes again. It only does it in high gear (Not in O.D., O.D. is off). Also while idling and giving throttle, the engine runs smooth up to about 2000 RPM, starts shaking somewhat, and smooths back out around 2400 rpm's. I have changed the plugs and fuel filter and getting ready to change the plugwires. Could a bad spark make it seem as if the transmisson has a problem? Also If the wires don't cure it, where should I look next? The truck has 76,000 miles on it. The trans fluid was changed about 4,000 miles ago, but I don't think they drained the Torque Conv. I really can't afford to take it to the dealer or a shop so I'm having to track it down asking other people their thoughts. ANY HELP would be great! Thanks!

 

Yes, bad plug wires could do what you described.

And you have the 4R70W transmission. That is the only automatic that has been offered with the 4.6L.

 

Thanks Mark!, I just changed the plug wires. So, Now I have changed the plugs, wires and the fuel filter. Still having the same problem. I plan to do a "complete transmisson fluid" change later. Does anyone have any idea what it might be if a fluid change doesn't work? Thanks for any help I can get on this.

 

jason,

does it feel like the engine is misfiring (sputtering) when it shakes?

also, it is possible that it could be a motor/powertrain mount?

 

Hello TroyK thanks for your concern! It doesn't really seem like the engine is misfiring when it shakes. It's normal until it shifts to the last gear (OD Off). When I go up hill and it drops a gear, it works fine. I have check the drivetrain connection bolts and the torque conv. bolts. I did have the T.C. bolts get loose right before the warranty ran out 2 years ago. It did the same thing, shake here and there. After I changed my plug wires today, I test drove it, It worked fine for about 3 miles, then it started again. I'm thinking it might be the torque conv. but I really don't want to spend the money changing it when it might not be my problem. Any way to tell for sure if it is the T.C.? I would take it to the dealer but with the baby on the way, money has got real tight!! Thanks to everyone for there help on this!

 

what if you let it go into OD...does is shake then?

 

TroyK I haven't tried it in OD yet. I will try it in the morning when I go to work. I have to drive 20 Miles one way so I will be able to tell more about it. But since you brought this to my attention, Do you have any ideas on what it could be if it does or doesn't?
Thanks again!